diff --git a/src/ngx_http_upstream_check_module/check_1.20.1+.patch b/src/ngx_http_upstream_check_module/check_1.20.1+.patch
new file mode 100644
index 0000000..7e18510
--- /dev/null
+++ b/src/ngx_http_upstream_check_module/check_1.20.1+.patch
@@ -0,0 +1,240 @@
+diff --git a/src/http/modules/ngx_http_upstream_hash_module.c b/src/http/modules/ngx_http_upstream_hash_module.c
+index e741eb23..d7d288d9 100644
+--- a/src/http/modules/ngx_http_upstream_hash_module.c
++++ b/src/http/modules/ngx_http_upstream_hash_module.c
+@@ -9,6 +9,9 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
++#if (NGX_HTTP_UPSTREAM_CHECK)
++#include "ngx_http_upstream_check_module.h"
++#endif
+ 
+ typedef struct {
+     uint32_t                            hash;
+@@ -238,6 +241,14 @@ ngx_http_upstream_get_hash_peer(ngx_peer_connection_t *pc, void *data)
+             goto next;
+         }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++                       "get hash peer, check_index: %ui", peer->check_index);
++        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++            goto next;
++        }
++#endif
++
+         if (peer->max_fails
+             && peer->fails >= peer->max_fails
+             && now - peer->checked <= peer->fail_timeout)
+@@ -560,6 +571,15 @@ ngx_http_upstream_get_chash_peer(ngx_peer_connection_t *pc, void *data)
+                 continue;
+             }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++                           "get consistent_hash peer, check_index: %ui",
++                           peer->check_index);
++            if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++                continue;
++            }
++#endif
++
+             if (peer->server.len != server->len
+                 || ngx_strncmp(peer->server.data, server->data, server->len)
+                    != 0)
+diff --git a/src/http/modules/ngx_http_upstream_ip_hash_module.c b/src/http/modules/ngx_http_upstream_ip_hash_module.c
+index 1fa01d95..366aca9a 100644
+--- a/src/http/modules/ngx_http_upstream_ip_hash_module.c
++++ b/src/http/modules/ngx_http_upstream_ip_hash_module.c
+@@ -9,6 +9,9 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++#include "ngx_http_upstream_check_module.h"
++#endif
+ 
+ typedef struct {
+     /* the round robin data must be first */
+@@ -208,6 +211,15 @@ ngx_http_upstream_get_ip_hash_peer(ngx_peer_connection_t *pc, void *data)
+             goto next;
+         }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++            "get ip_hash peer, check_index: %ui",
++             peer->check_index);
++        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++            goto next;
++        }
++#endif
++
+         if (peer->max_fails
+             && peer->fails >= peer->max_fails
+             && now - peer->checked <= peer->fail_timeout)
+diff --git a/src/http/modules/ngx_http_upstream_least_conn_module.c b/src/http/modules/ngx_http_upstream_least_conn_module.c
+index ebe06276..35250354 100644
+--- a/src/http/modules/ngx_http_upstream_least_conn_module.c
++++ b/src/http/modules/ngx_http_upstream_least_conn_module.c
+@@ -9,6 +9,9 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++#include "ngx_http_upstream_check_module.h"
++#endif
+ 
+ static ngx_int_t ngx_http_upstream_init_least_conn_peer(ngx_http_request_t *r,
+     ngx_http_upstream_srv_conf_t *us);
+@@ -147,6 +150,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
+             continue;
+         }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++                "get least_conn peer, check_index: %ui",
++                peer->check_index);
++
++        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++            continue;
++        }
++#endif
++
+         if (peer->max_fails
+             && peer->fails >= peer->max_fails
+             && now - peer->checked <= peer->fail_timeout)
+@@ -202,6 +215,16 @@ ngx_http_upstream_get_least_conn_peer(ngx_peer_connection_t *pc, void *data)
+                 continue;
+             }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++            ngx_log_debug1(NGX_LOG_DEBUG_HTTP, pc->log, 0,
++                    "get least_conn peer, check_index: %ui",
++                    peer->check_index);
++
++            if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++                continue;
++            }
++#endif
++
+             if (peer->conns * best->weight != best->conns * peer->weight) {
+                 continue;
+             }
+diff --git a/src/http/ngx_http_upstream_round_robin.c b/src/http/ngx_http_upstream_round_robin.c
+index 1f15fae5..d507a0e3 100644
+--- a/src/http/ngx_http_upstream_round_robin.c
++++ b/src/http/ngx_http_upstream_round_robin.c
+@@ -9,6 +9,9 @@
+ #include <ngx_core.h>
+ #include <ngx_http.h>
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++#include "ngx_http_upstream_check_module.h"
++#endif
+ 
+ #define ngx_http_upstream_tries(p) ((p)->tries                                \
+                                     + ((p)->next ? (p)->next->tries : 0))
+@@ -104,6 +107,15 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
+                 peer[n].down = server[i].down;
+                 peer[n].server = server[i].name;
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++                if (!server[i].down) {
++                    peer[n].check_index =
++                        ngx_http_upstream_check_add_peer(cf, us, &server[i].addrs[j]);
++                } else {
++                    peer[n].check_index = (ngx_uint_t) NGX_ERROR;
++                }
++#endif
++
+                 *peerp = &peer[n];
+                 peerp = &peer[n].next;
+                 n++;
+@@ -174,6 +186,16 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
+                 peer[n].down = server[i].down;
+                 peer[n].server = server[i].name;
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++                if (!server[i].down) {
++                    peer[n].check_index =
++                        ngx_http_upstream_check_add_peer(cf, us, &server[i].addrs[j]);
++                }
++                else {
++                    peer[n].check_index = (ngx_uint_t) NGX_ERROR;
++                }
++#endif
++
+                 *peerp = &peer[n];
+                 peerp = &peer[n].next;
+                 n++;
+@@ -241,6 +263,9 @@ ngx_http_upstream_init_round_robin(ngx_conf_t *cf,
+         peer[i].max_conns = 0;
+         peer[i].max_fails = 1;
+         peer[i].fail_timeout = 10;
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        peer[i].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+         *peerp = &peer[i];
+         peerp = &peer[i].next;
+     }
+@@ -358,6 +383,9 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
+         peer[0].max_conns = 0;
+         peer[0].max_fails = 1;
+         peer[0].fail_timeout = 10;
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        peer[0].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+         peers->peer = peer;
+ 
+     } else {
+@@ -392,6 +420,9 @@ ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
+             peer[i].max_conns = 0;
+             peer[i].max_fails = 1;
+             peer[i].fail_timeout = 10;
++#if (NGX_HTTP_UPSTREAM_CHECK)
++            peer[i].check_index = (ngx_uint_t) NGX_ERROR;
++#endif
+             *peerp = &peer[i];
+             peerp = &peer[i].next;
+         }
+@@ -457,6 +488,12 @@ ngx_http_upstream_get_round_robin_peer(ngx_peer_connection_t *pc, void *data)
+             goto failed;
+         }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++            goto failed;
++        }
++#endif
++
+         rrp->current = peer;
+ 
+     } else {
+@@ -551,6 +588,12 @@ ngx_http_upstream_get_peer(ngx_http_upstream_rr_peer_data_t *rrp)
+             continue;
+         }
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++        if (ngx_http_upstream_check_peer_down(peer->check_index)) {
++            continue;
++        }
++#endif
++
+         if (peer->max_fails
+             && peer->fails >= peer->max_fails
+             && now - peer->checked <= peer->fail_timeout)
+diff --git a/src/http/ngx_http_upstream_round_robin.h b/src/http/ngx_http_upstream_round_robin.h
+index 922ceaa0..14d8ad86 100644
+--- a/src/http/ngx_http_upstream_round_robin.h
++++ b/src/http/ngx_http_upstream_round_robin.h
+@@ -38,6 +38,10 @@ struct ngx_http_upstream_rr_peer_s {
+     ngx_msec_t                      slow_start;
+     ngx_msec_t                      start_time;
+ 
++#if (NGX_HTTP_UPSTREAM_CHECK)
++    ngx_uint_t                      check_index;
++#endif
++
+     ngx_uint_t                      down;
+ 
+ #if (NGX_HTTP_SSL || NGX_COMPAT)